The first group of Michael Jackson fans have just arrived to Forest Lawn Memorial Park in Glendale, California — where MJ is entombed — in preparation for the one year anniversary of the singer’s death.

We’re told the cemetery is expecting thousands of people to show up in the next 24 hours.

Michael Jackson’s estate is lashing out at the people behind a new MJ documentary set to debut in Japan tomorrow — claiming fans are being duped into believing the flick was authorized by Team MJ.

The estate has released a scathing statement claiming the movie is being promoted in a way that is misleading MJ’s fans into believing the film — shot by former MJ confidante Marc Schaffel — was properly authorized.

The estate also makes it clear it doesn’t endorse the flick and none of the profits will benefit MJ’s children. They also note that the movie is not allowed to contain any of Michael’s music.

Schaffel doesn’t appear to be bothered — the above photo was taken moments ago at the movie premier in Tokyo … where Schaffel took the stage and told fans Katherine Jackson sent along her best wishes.

The co-author of a new book on Michael Jackson has threatened to sue the Michael Jackson estate for allegedly trying to discredit the book.

Howard Mann (center, along with Katherine and two others) — a businessman who has made money on nude online gambling and nude wrestling — hooked up with Katherine Jackson to create a coffee table book called “Never Can Say Goodbye.”

Estate lawyer Howard Weitzman told TMZ earlier this week, Mann had no right “to exploit any estate assets” and would take “whatever action is necessary to prevent him from unlawfully profiting.”

Mann’s attorney now tells TMZ, “The comments by the lawyers for the Estate of Michael Jackson are designed to create fear and ambiguity and may impede our ability to maximize the profits that Vintage Pop (the publisher) and the beneficiaries of the Estate are entitled to enjoy. These actions are torturous interference and will NOT be accepted and will result [in] litigation to recover the damages against our company.”

Weitzman tells TMZ, “The estate will continue to protect its assets when appropriate,” adding, “If Mr. Mann or his attorney want to communicate with me, they can contact me directly.”

As we previously reported, the bash is being thrown by a website called VoicePlate.com — but no one could identify the person responsible for pulling the strings. It’s also unclear who convinced Katherine Jackson to record that awkward, scripted promotional video for the tribute.

But now — a clue … and it all has to do with the featured entertainment at the MJ tribute … a band called the Chi-Lites — they had a couple of hits in the ’70s, including “Oh Girl” and “Have You Seen Her.”

If you recall, just days after MJ died … Joe Jackson shamelessly held a news conference to introduce his new business partner, Marshall Thompson … a member of the Chi-Lites.

Think it’s coincidence that the band got a brand new gig … at an MJ event?

The Jackson family compound in Encino is gonna be locked down tighter than Fort Knox on the anniversary ofMichael Jackson‘s death … because we’re told the LAPD is preparing for an onslaught of MJ faithful.

According to the LAPD, there will be 30 to 40 officers — some uniformed, some undercover — patrolling a one block area around the Jackson home on Friday, Saturday, and Sunday.

We’re also told other precautions will be taken — including “no parking” signs around the house and a ban on all MJ merch sales in the area … the same rules that will be enforced at Forest Lawn Cemetery.

The LAPD says 3,000 to 4,000 shirts were confiscated last year after Michael died — so you’ve been warned.